由于 apache2.4 与 apache2.2 的虚拟主机配置写法不同导致。

apache2.2的写法：

<VirtualHost *:80>
ServerName demo.com
DocumentRoot \"/www\"
DirectoryIndex index.html index.php
<Directory \"/www\">
Options -Indexes +FollowSymlinks
AllowOverride All
Order deny,allow
Allow from all
</Directory>
</VirtualHost>

如果在2.4中使用以上写法就会有apache AH01630: client denied by server configuration错误。

<VirtualHost *:80>
ServerName  demo.com
DocumentRoot \"/www\"
DirectoryIndex index.html index.php
<Directory \"/www\">
Options -Indexes +FollowSymlinks
AllowOverride All
Require all granted
</Directory